Water based ink for ball point pen

ABSTRACT

An action of the preventing drying at a pen tip without using water-soluble organic solvents such as glycols, glycerin and glycol ethers which have so far been used for a water based ink for a ball point pen is allotted to at least one selected from the group consisting of a reducing sugar comprising maltitol as a principal component, a reducing sugar comprising sorbitol as a principal component, reducing dextrin, reducing maltodextrin, α-cyclodextrin, β-cyclodextrin and maltosylcyclodextrin, and the actions of inhibiting feathering of the drawn lines, improving discharge stability of the ink and maintaining the lubricity are allotted to at least one selected from the group consisting of an alkylene oxide adduct of polyglycerin, an alkylene oxide adduct of glycerin and an alkylene oxide adduct of trimethylolpropane. Further, a viscosity-controlling agent is added thereto to thereby prepare a water based ink for a ball point pen which has feathering resistance, good writing feeling and high discharge stability and which is excellent in drying prevention effect at a pen tip.

TECHNICAL FIELD

The present invention relates to a water based ink for a ball point pen.

BACKGROUND ART

Water based inks have so far had the problem that if moisture thereof isevaporated, for example, dissolved substances and dispersed componentscontained in the inks are concentrated, deposited, dried and solidifiedto bring about clogging at the tips of the writing instruments and toincrease a viscosity of the inks, thereby causing troubles in writing.

In this connection, it is proposed to add to a water based ink for aball point pen, scarcely volatile dye-solubilizing agents ordye-dissolving aids such as urea, thiourea, polyhydric alcohols orderivatives thereof, tetrahydrofurfuryl alcohol,4-methoxy-4-methylpentane-2-one, ethylene oxide adducts ofp-toluenesulfonamide and thiodiethanolalkynolamine.

However, these urea, thiourea and polyhydric alcohols have not been ableto provide satisfactory water based inks because of the reasons thatthey have an insufficient drying prevention effect or they have toxicityand are unsuitable for additives and that they allow a viscosity of theink to grow large to bring about inferior follow-up of the ink.

Proposed in Japanese Patent Application NO. 9-181391 by the presentapplicant was a pseudoplastic water based ink for a ball point pencomprising a colorant, water, a water-soluble organic solvent and aviscosity-controlling agent and reducing dextrin or reducingmaltodextrin. These inks using a water-soluble organic solvent such asglycols, glycerin and glycol ethers are increased in feathering of thedrawn lines. Further, they do not provide sufficient lubricity, so thata ball point pen using them is increased in frictional resistancebetween the ball and the ball housing to abrade the ball housing andtherefore has the defect that the writing property is notably reduced,such that the ball sinks and the ink is discharged unevenly.

Further, proposed in Japanese Patent Application Laid-Open No. 8-12916is an ink comprising titanium oxide, a thickening water-soluble resin, abinder, a sugar alcohol and water, wherein a viscosity value is 6,000 to50,000 mPa·s, and a viscosity index obtained according to a differencein a revolution of a viscometer is 2 or more. However, even an inkhaving such a high viscosity index does not solve the problems of afollow-up property in quick writing and splitting of the drawn lines.Further, it contains only a white pigment as a colorant and has theproblem that a marking ability is inferior.

Further, it is proposed in Japanese Patent Application Laid-Open No.5-186730 to add an alkylene oxide adduct of polyglycerin in order toimprove feathering. However, though the adding of the alkylene oxideadduct of polyglycerin improves the feathering resistance and thewriting feeling, the drying prevention effect at a pen tip is notprovided. Accordingly, there remains unsolved the problem that when thepen is left standing with the cap off, moisture is vaporized from thepen tip and the pen tip is dried, so that the writing property isreduced.

An object of the present invention is to solve the problems describedabove, that is, to provide a water based ink for a ball point pen whichis good in feathering resistance and writing feeling and has highdischarge stability of the ink and which is excellent in a dryingprevention effect at a pen tip.

DISCLOSURE OF THE INVENTION

Intensive researches continued by the present inventors in order tosolve the problems described above have resulted in finding that thepart of the preventing of drying at a pen tip which has so far been anaction exerted by water-soluble organic solvents is allotted to at leastone selected from the group consisting of a reducing sugar comprisingmaltitol as a principal component, a reducing sugar comprising sorbitolas a principal component, reducing dextrin, reducing maltodextrin,α-cyclodextrin, β-cyclodextrin and maltosylcyclodextrin without usingwater-soluble organic solvents such as glycols, glycerin and glycolethers which have so far been used for a water based ink for a ballpoint pen, and the parts of actions to inhibit feathering of the drawnlines, to improve a discharge stability of the ink and to maintain thelubricity are allotted to at least one selected from the groupconsisting of an alkylene oxide adduct of polyglycerin, an alkyleneoxide adduct of glycerin and an alkylene oxide adduct oftrimethylolpropane, whereby the respective effects are improved moremarkedly than ever, and a synergistic effect of raising the stabilitywith the passage of time is produced.

BEST MODE FOR CARRYING OUT THE INVENTION

A reducing sugar comprising maltitol as a principal component, areducing sugar comprising sorbitol as a principal component, reducingdextrin, reducing maltodextrin, α-cyclodextrin, β-cyclodextrin andmaltosylcyclodextrin which are used in the present invention are sugarswhich are generally used as edible sweetenings and which are non-toxicand safe and have the characteristics that they have high solubility inwater and very excellent water retention.

Further, a water based ink for a writing instrument containing thesecompositions is safe and not varied in a viscosity and a pH with thepassage of time and makes it possible to improve the writing feeling andthe drying resistance. Further, they do not exert an adverse effect onink composition materials generally used and do not change a hydrogenion concentration in the ink, so that they do not exert an adverseeffect as well on anionic and cationic materials and therefore have theadvantage that a colorant can be optionally selected from all waterbased dyes and organic or inorganic pigments.

With respect to a content of a reducing sugar comprising maltitol as aprincipal component, a reducing sugar comprising sorbitol as a principalcomponent, reducing dextrin, reducing maltodextrin, α-cyclodextrin,β-cyclodextrin and maltosylcyclodextrin in the ink in the presentinvention, at least one of them is added in an amount of 0.5 to 20% byweight based on the total amount of the ink. If the content is smallerthan 0.5% by weight, the effect of the drying resistance is reduced, andif it is more than 20% by weight, the spinnability is intensified toreduce the writing feeling.

On the other hand, at least one selected from the group consisting of analkylene oxide adduct of polyglycerin, an alkylene oxide adduct ofglycerin and an alkylene oxide adduct of trimethylolpropane, and amixture thereof have a purpose to elevate the feathering resistance andthe lubricity and to improve the discharge stability of the ink, and thecombination of blending with the reducing sugar and the reducing dextrindescribed above produces a synergistic effect of raising the dryingresistance at a pen tip (hereinafter referred to as a non-dryingproperty) and the stability with the passage of time. A content thereofis 0.5 to 40% by weight, more preferably 5 to 20% by weight based on thewhole composition.

There can be used as the colorant all dyes which are soluble ordispersed in water, and all pigments such as titanium oxide, publiclyknown inorganic and organic pigments, pseudo-pigments obtained bycoloring resin emulsions with dyes, and white plastic pigments.

Specific examples thereof include acid dyes such as Eosine, Phloxine,Water Yellow #6-C, acid red, Water Blue #105, Brilliant Blue FCF andNigrosine NB, direct dyes such as Direct Black 154, Direct Sky Blue 5Band Violet BB, and basic dyes such as Rhodamine and Methyl Violet.

Inorganic pigments include, for example, carbon black and metal powders.

Organic pigments include, for example, azo lake, insoluble azo pigments,chelate azo pigments, phthalocyanine pigments, perylene and perinonepigments, anthraquinone pigments, quinacridone pigments, dye lakes,nitro pigments and nitroso pigments.

To be specific, included are inorganic pigments such as carbon black,titanium black, zinc oxide, red iron oxide, chromium oxide, black ironoxide, cobalt blue, yellow iron oxide, viridian, zinc sulfide,lithopone, cadmium yellow, vermilion, cadmium red, chrome yellow,molybdate orange, zinc chromate, strontium chromate, white carbon, clay,talc, ultramarine, precipitated barium sulfate, baryte powder, calciumcarbonate, white lead, Prussian blue, manganese violet, aluminum powderand bronze powder;

C. I. Pigment Blue 1, C. I. Pigment Blue 15, C. I. Pigment Blue 17, C.I. Pigment Blue 27, C. I. Pigment Red 5, C. I. Pigment Red 22, C. I.Pigment Red 38, C. I. Pigment Red 48, C. I. Pigment Red 49, C. I.Pigment Red 53, C. I. Pigment Red 57, C. I. Pigment Red 81, C. I.Pigment Red 104, C. I. Pigment Red 146, C. I. Pigment Red 245, C. I.Pigment Yellow 1, C. I. Pigment Yellow 3, C. I. Pigment Yellow 12, C. I.Pigment Yellow 13, C. I. Pigment Yellow 14, C. I. Pigment Yellow 17, C.I. Pigment Yellow 34, C. I. Pigment Yellow 55, C. I. Pigment Yellow 74,C. I. Pigment Yellow 83, C. I. Pigment Yellow 95, C. I. Pigment Yellow166, C. I. Pigment Yellow 167, C. I. Pigment Orange 5, C. I. PigmentOrange 13, C. I. Pigment Orange 16, C. I. Pigment Violet 1, C. I.Pigment Violet 3, C. I. Pigment Violet 19, C. I. Pigment Violet 23, C.I. Pigment Violet 50, and C. I. Pigment Green 7.

The use amount of the colorant is preferably 0.1 to 30% by weight basedon the total amount of the ink.

Acryl base synthetic polymers, natural gums, cellulose andpolysaccharides can be used as the viscosity-controlling agent.

Included are products on the market such as, for example,

“Junron PW-111” manufactured by Nippon Pure Chemicals Ind. Co., Ltd.,

“Hiviswako 104” manufactured by Wako Pure Chemical Industries, Ltd.,

“KELZAN”, “KELZAN AR”, “KIA96”, “KIA112”, “RHEOZAN” AND “K7C233”manufactured by Sansho Co., Ltd.,

“JUGAR HP-8”, “JUGAR HP-60”, “RHODOPOL23” and

“RHODOPOL50MC” manufactured by Rhone Poulenc Japan, Ltd., and

“Echo Gum GH” manufactured by Dainippon Pharmaceutical Co., Ltd.

The content thereof is suitably increased or decreased depending on theviscosity of the ink.

If the ink composition of the present invention has a viscosity of 4,000mPa·s or more at a low shearing rate, the discharge amount of the ink inwriting is reduced, and therefore such a viscosity is not preferred.

Accordingly, it is effective that the viscosity at a shearing rate of3.84 s⁻¹ falls in a range of 200 to 4,000 mPa·s, preferably 300 to 3,000mPa·s and more preferably 600 to 2,500 mPa·s.

The range of the shearing rate which can be applied to a conventionalrotary type viscometer is 1.92 to 3.84 s⁻¹, and in the presentinvention, a measured value at 3.84 s⁻¹ shall be employed considering astability of the measured value.

In addition thereto, there can suitably be selected and used, ifnecessary,

dispersants (water-soluble polymers, etc.) for pigments,

pH adjusting agents such as ammonia, urea, monoethanolamine,diethanolamine, triethanolamine, alkali metal salts of carbonic acid andphosphoric acid such as sodium tripolyphosphate and sodium carbonate,and hydroxides of alkali metals such as sodium hydroxide;

preservatives or fungicides such as phenol, sodium omadine, sodiumpentachlorophenol, 1,2-benzisothiazoline-3-one,2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, alkali metal salts ofbenzoic acid, sorbic acid and dehydroacetic acid such as sodiumbenzoate, and benzimidazole base compounds;

rust preventives such as benzotriazole, dicyclohexylammonium nitrite,diisopropylammonium nitrite and tolyltriazole;

derivatives of polyoxyethylene, polyoxypropylene orpolyoxyethylenepolyoxypropylene such as polyoxyethylene lauryl ether,sorbitan derivatives such as sorbitan monooleate, and surfactants havingfluorinated alkyl groups such as perfluoroalkylphosphoric acid esters;and

lubricants, wetting agents and defoaming agents such aspolyether-modified silicones including polyethylene glycol adducts ofdimethylpolysiloxane.

EXAMPLES

The present invention shall more specifically be explained below withreference to examples, but the present invention shall by no means berestricted by these examples.

Blending proportions in the examples and the comparative examples andthe evaluation results of inks produced based on the formations areshown in Table 1 and Table 2. Water based inks for a ball point penshown in the respective examples and comparative examples were obtainedby stirring the respective compositions and then filtering them.

(1) Blending Feature of Example 1

Black ink

Maltitol

Propylene oxide 4 moles adduct of diglycerin

(2) Blending Feature of Example 2

Blue ink

Reducing dextrin

Ethylene oxide 4 moles adduct of diglycerin

(3) Blending Feature of Example 3

Black ink

Sorbitol

Propylene oxide 13 moles adduct of diglycerin

(4) Blending Feature of Example 4

Blue ink

Maltosylcyclodextrin

Ethylene oxide 13 moles adduct of diglycerin

Propylene oxide 10 moles adduct of triglycerin

(5) Blending Feature of Example 5

Blue ink

Titanium oxide

Reducing dextrin

Propylene oxide 4 moles adduct of diglycerin

Ethylene oxide 13 moles adduct of diglycerin

Viscosity-controlling agent (xanthan gum) 0.3% by weight

(6) Blending Feature of Comparative Example 1

Glycerin was blended in place of maltitol and the propylene oxide 4moles adduct of diglycerin in Example 1.

Black ink

Glycerin

(7) Blending Feature of Comparative Example 2

Reducing dextrin in Example 2 was removed.

Blue ink

Propylene oxide 4 moles adduct of diglycerin

(8) Blending Feature of Comparative Example 3

Glycerin was blended in place of the propylene oxide 4 moles adduct ofdiglycerin in Example 1.

Black ink

Maltitol

Glycerin

(9) Blending Feature of Comparative Example 4

Maltosylcyclodextrin of Example 4 was removed, and 5.0% by weight ofurea was blended.

Blue ink

Ethylene oxide 13 moles adduct of diglycerin

Propylene oxide 10 moles adduct of triglycerin

Urea

Nine kinds of the inks obtained in the examples and the comparativeexamples described above were used to carry out the following tests, andthe results described in Table 1 and Table 2 were obtained.

Evaluation Standards:

(1) Ink Viscosity:

The viscosity was measured by means of an EMD type viscometer at ashearing rate of 3.84 sol within a week after preparing the ink.

(2) Feathering Resistance:

The inks obtained in the respective formations were charged respectivelyinto ball point pens having a ball diameter of 0.7 mm, and “spiralwriting” was carry out on writing paper to evaluate a feathering stateof the drawn lines with eyes according to the following criteria:

∘: no feathering observed and distinct writings

Δ: feathering observed and indistinct writings

X: marked feathering observed and very indistinct writings

(3) Non-drying Property:

The inks obtained in the respective formations were charged respectivelyinto ball point pens having a ball diameter of 0.7 mm, and the ballpoint pens were left standing sideways with the caps off in a constanttemperature chamber at 25° C. and a humidity of 65%. “Spiral writing”was carry out on writing paper after 2 weeks and one month respectivelyto evaluate a grade of the drawn lines according to the followingcriteria:

∘: the drawn lines have no starving and can be written well

∘′: the drawn lines have slight starving and can be written almost well

Δ: the drawn lines have marked starving, and scratching is caused inwriting

X: hardly capable of writing

(4) Writing Feeling:

The inks obtained in the respective formations were charged respectivelyinto ball point pens having a ball diameter of 0.7 mm, and “spiralwriting” was carry out on writing paper to evaluate the writing feelingaccording to the following criteria:

∘: smooth and stable writing feeling

Δ: stiff and hard writing feeling

X: stiff and hard writing feeling, and skip and

directional error are observed

(5) Ink Discharge Stability:

The inks obtained in the respective formations were charged respectivelyinto ball point pens having a ball diameter of 0.7 mm, and “spiralwriting” was carry out on writing paper up to exhaustion of the ink bymenas of a write test machine to evaluate the ink discharge stabilityaccording to the following criteria:

∘: possible of writing at a stable discharge rate up to exhaustion ofthe ink

Δ: discharge rate is decreased or increased in the middle of writing andstable writing is impossible

X: incapable of writing in the middle of writing

(6) Ink Follow-up Property:

The inks obtained in the respective formations were charged respectivelyinto ball point pens having a ball diameter of 0.7 mm, and “spiralwriting” was carry out on writing paper at a twice rate as quick asusual to evaluate a grade of the drawn lines according to the followingcriteria:

∘: the drawn lines have no starving and can be written well

Δ: the drawn lines have slight starving

X: hardly capable of writing

TABLE 1 Example 1 2 3 4 5 Carbon black 8.0 8.0 Phthalocyanine blue 7.57.5 0.2 Titanium oxide 22.0 Styrene-maleic acid 3.0 1.5 resin ammoniumsalt Styrene-acrylic acid 2.5 3.0 2.5 0.5 resin ammonium salt Maltitol4.0 Sorbitol 2.0 Reducing dextrin 3.0 2.0 4.0 Maltosylcyclodextrin 5.0Propylene oxide 4 mole 15.0 15.0 5.0 adduct of diglycerin Ethylene oxide13 mole 13.0 5.0 7.0 adduct of diglycerin Propylene oxide 10 mole 5.0adduct of triglycerin Potash soap 0.3 0.3 0.3 0.3 0.3 Glycerin UreaViscosity-controlling 0.3 0.3 0.3 0.3 agent (acryl base syntheticpolymer) Viscosity-controlling 0.3 agent (xanthan gum)Aminomethylpropanol 0.3 0.3 0.3 0.3 0.3 Bioden 0.2 0.2 0.2 0.2 0.2Benzotriazole 0.2 0.2 0.2 0.2 0.2 Ion-exchanged water Balance BalanceBalance Balance Balance Total 100.0 100.0 100.0 100.0 100.0 Inkviscosity 3.84 s⁻¹ 700 500 700 600 2500 (mPa.s) Feathering resistance ◯◯ ◯ ◯ ◯ Non-drying property 25° C. 65% 2 weeks ◯ ◯ ◯ ◯ ◯ one month ◯ ◯ ◯◯′ ◯′ Writing feeling ◯ ◯ ◯ ◯ ◯ Abrasion of ball None None None NoneNone housing after writing Viscosity change after None None None NoneNone one month at 50° C. Ink discharge stability ◯ ◯ ◯ ◯ ◯ Ink follow-upproperty ◯ ◯ ◯ ◯ ◯

TABLE 2 Comparative Example 1 2 3 4 Carbon black 8.0 8.0 Phthalocyanineblue 7.5 7.5 Titanium oxide Styrene-maleic acid 3.0 resin ammonium saltStyrene-acrylic acid 2.5 3.0 2.5 resin ammonium salt Maltitol 4.0Sorbitol Reducing dextrin Maltosylcyclodextrin Propylene oxide 4 mole15.0 adduct of diglycerin Ethylene oxide 13 mole 5.0 adduct ofdiglycerin Propylene oxide 10 mole 5.0 adduct of triglycerin Potash soap0.3 0.3 0.3 0.3 Glycerin 15.0 15.0 Urea 5.0 Viscosity-controlling 0.30.3 0.3 0.3 agent (acryl base synthetic polymer) Viscosity controllingagent (xanthan gum) Aminomethylpropanol 0.3 0.3 0.3 0.3 Bioden 0.2 0.20.2 0.2 Benzotriazole 0.2 0.2 0.2 0.2 Ion-exchanged water BalanceBalance Balance Balance Total 100.0 100.0 100.0 100.0 Ink viscosity 3.84s⁻¹ 650 500 600 900 (mPa.s) Feathering resistance Δ ◯ Δ ◯ Non-dryingproperty 25° C. 65% 2 weeks X Δ ◯ ◯ one month X Δ Δ X Writing feeling ΔΔ Δ Δ Abrasion of ball Present None Present None housing after writingViscosity change after Up None Up None one month at 50° C. Ink dischargestability Δ ◯ Δ Δ Ink follow-up property ◯ ◯ ◯ ◯

Industrial Applicability

The water based ink of the present invention used for a ball point penprovides good writing feeling as well as high discharge stability of theink, and is excellent in a drying prevention effect at a pen tip.

What is claimed is:
 1. A water based ink for a ball point pen comprising0.5 to 20% by weight based on the total composition, of at least oneselected from the group consisting of a reducing sugar comprisingmaltitol as a principal component, a reducing sugar comprising sorbitolas a principal component, reducing dextrin, reducing maltodextrin,α-cyclodextrin, β-cyclodextrin and maltosylcyclodextrin and 0.5 to 40%by weight based on the total composition, of at least one selected fromthe group consisting of an alkylene oxide adduct of polyglycerin, analkylene oxide adduct of glycerin and an alkylene oxide adduct oftrimethylolpropane, and further comprising a colorant, aviscosity-controlling agent and water.
 2. The water based ink for a ballpoint pen as described in claim 1, comprising at least one selected fromthe group consisting of synthetic polymers, natural gums, cellulose andpolysaccharides as the viscosity-controlling agent, wherein theviscosity at a shearing rate of 3.84 so⁻¹ falls in a range of 200 to4,000 mPa·s.